Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
  • H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
  • H04W16/10—Dynamic resource partitioning
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/20—Control channels or signalling for resource management
  • H04W72/27—Control channels or signalling for resource management between access points
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/50—Allocation or scheduling criteria for wireless resources
  • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
  • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference

Definitions

• LTE Long Term Evolution
• 3GPP Third Generation Partnership Project
• E-UTRA Evolved UTRA
• UTRAN UTRAN - Radio interface protocol aspects
• This invention arose in the context of developments underway in the LTE but is not necessarily limited to that context and could, for instance, be applied in any wireless communications context such as a WiMAX context.
• An example of the E-UTRAN architecture is illustrated in Fig. 1.
• the eNB may host functions such as radio resource management (radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to UEs in both uplink and downlink) , selection of a mobility management entity (MME) at UE attachment, routing of user plane data towards the user plane entity (UPE) , scheduling and transmission of paging messages (originated from the MME) , scheduling and transmission of broadcast information (originated from the MME or O&M) , and measurement and measurement reporting configuration for mobility and scheduling.
• radio resource management radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to UEs in both uplink and downlink
• MME mobility management entity
• UPE user plane entity
• scheduling and transmission of paging messages originated from the MME
• scheduling and transmission of broadcast information originated from the MME or O&M
• measurement and measurement reporting configuration for mobility and scheduling.
• the MME/UPE may host functions such as the following: distribution of paging messages to the eNBs, security control, IP header compression and encryption of user data streams; termination of U-plane packets for paging reasons; switching of U-plane for support of UE mobility, idle state mobility control, EPS (Evolved Packet System) bearer control, and ciphering and integrity protection of NAS signaling.
• the invention is related to LTE, although the solution of the present invention may also be applicable to present and future systems other than LTE.
• OFDM Orthogonal Frequency Division Multiplexing
• SC-FDMA Single Carrier Frequency Division Multiple Access
• SC-FDMA utilizes single carrier modulation and frequency domain equalization in a technique that has similar performance and essentially the same overall complexity as OFDM.
• SC-FDMA can be regarded as DFT- precoded or OFT-spread OFDM.
• An advantage over OFDM is that the SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. The lower PAPR of SC-FDMA greatly benefits the mobile terminal in terms of transmit power efficiency.
• PAPR peak-to-average power ratio
• both OFDMA and SC-FDMA use block-based modulation, divide the transmission bandwidth into smaller subcarriers, carry out channel equalization in the frequency domain and add a cyclic prefix (CP) (guard interval) to overcome Inter-Block Interference (IBI) and to convert linear convolution of the channel impulse response to a circular one for easy frequency domain equalization at the receiver end.
• CP cyclic prefix
• IBI Inter-Block Interference
• Intercell Interference is a key problem in cellular communication systems such as LTE. Both the uplink and downlink are affected. In the downlink, a User Equipment (UE) gets interfered by neighboring Base Stations (BSs) , i.e., eNBs . This generates problems in UEs at the cell edge since the interference is largest there. In the uplink, a base station receives interference by UEs which are connected to other BSs. This interference is worst, if the "aggressor" UE is close to the cell edge. Close UEs in the cell of interest may well have sufficient power to drown out the worst-case interference from foreign edge UEs, but own edge UEs probably won't. The key to an efficient system is a smart management of the intercell interference. Note that data rates at the cell edge are a crucial design criterion for any communication system.
• interference averaging to mitigate inter-cell interference is not an option in LTE.
• Soft Handover which is an efficient method for interference mitigation
• Another solution could be interference cancellation, where the BS tries to cancel interference from aggressor UEs exploiting e.g. the spatial signature of the interference. Those methods are typically vendor-specific and need not to be standardized. It has also already been mentioned above that a centralized interference coordination scheme has been excluded.
• the measurement used for the OI is to be specified in 3GPP TS 36.214.
• the idea of the OI is to give an indication to other cells if the interference in particular parts ("clusters") of the spectrum is too high.
• a cluster may for instance be part of a spectrum, i.e., a particular frequency region consisting of several physical radio blocks.
• the OI is frequency resolved, i.e., there is one OI per cluster.
• Every BS can receive OIs from every surrounding cell. It may well happen, that every cell requests another cluster with low interference such that no cluster is left for high interference. In such a case, the BS has to violate/ignore some OIs if it wants to schedule cell edge users.
• a goal is to design the signalling and the reaction thereto such that every base station (BS) is rewarded if it shows a cooperative behavior, and therefore the BSs should be motivated to do so.
• BS base station
• apparatus for a cell of a cellular system comprising a transmitter for informing surrounding cells about a resource allocation strategy of said informing cell for allocating orthogonal resources of the informing cell; a receiver for receiving resource allocation strategies from said surrounding cells indicative of allocation strategies of said surrounding cells for allocating orthogonal resources of said surrounding cells; and a signal processor for allocating said orthogonal resources according to both said resource allocation strategy of the informing cell and the resource allocation strategies received from the surrounding cells so as to reduce interference in the system.
• the cell informs its strategy comprising allocating a frequency range where it will produce small interference, that is, allocating said frequency range to user equipment near a cell center.
• apparatus for a cell of a cellular system is configured to determine a resource allocation strategy of said cell for allocating orthogonal resources of the cell, to check resource allocation strategies of surrounding cells indicative of allocation strategies of said surrounding cells for allocating orthogonal resources of said surrounding cells, and to allocate said orthogonal resources according to both said resource allocation strategy of the cell and the resource allocation strategies of the surrounding cells.
• the cell may determine said strategy by allocating a frequency range where it will produce small interference, that is, where it allocates said frequency range to user equipment near a cell center.
• apparatus comprises means for a cell of a cellular system for informing surrounding cells about a resource allocation strategy of said informing cell for allocating orthogonal resources of the informing cell, said informing cell also comprising means for receiving resource allocation strategies from said surrounding cells indicative of allocation strategies of said surrounding cells for allocating orthogonal resources of said surrounding cells, and said informing cell comprising means allocating said orthogonal resources of the informing cell according to both said resource allocation strategy of the informing cell and the resource allocation strategies received from the surrounding cells so as to reduce interference in the system.
• apparatus comprises means for a cell of a cellular system to determine a resource allocation strategy of said cell for allocating orthogonal resources of the cell, said apparatus also comprises means for checking resource allocation strategies of surrounding cells indicative of allocation strategies of said surrounding cells for allocating orthogonal resources of said surrounding cells, and said apparatus further comprises means for allocating said orthogonal resources of the cell according to both said resource allocation strategy of the cell and the resource allocation strategies of the surrounding cells.
• Fig. 2 shows the present invention applied to the uplink in a cellular system.
• Fig. 3 is a flowchart showing one way to carry out the present invention in a base station.
• Fig. 4 shows components of a base station in communication with user equipment in a cell and another, neighboring base station in its own cell.
• Fig. 5 shows details of a signal processor.
• a cell would try to concentrate close UEs into a particular cluster, and indicates that to its neighbors. From a game theory perspective, this would likely induce the most cooperative behavior and therefore should achieve the maximum system gain.
• a cell could signal those clusters where it produces high (rather than low) interference. This would be more like an "overload warning.” Other cells would be informed that they should not use those clusters for their own edge users. This would be close to the current discussion with the small difference that we do not request and rely on a particular behavior. This would be less cooperative from the game theory perspective, but may be a viable option too.
• Fig 3 is a flowchart showing steps that may be carried out in a base station to inform its surrounding neighbors about its resource allocation strategy.
• a base station determines its own resource allocation strategy.
• it then informs surrounding cells about its own resource allocation strategy, e.g., for allocating orthogonal resources of the informing cell.
• the step 30 may be skipped if the strategy has already been informed in the past and is a static or semi-static strategy.
• the informing cell may also check resource allocation strategies of the surrounding cells indicative of allocation strategies of the surrounding cells, e.g., for allocating orthogonal resources of the surrounding cells. These strategies may be more or less permanent (static or semi-static) strategies and may already have been communicated to the base station.
• step 32 involves a communication with one or more surrounding base stations to find out (send, receive, or both send and receive) current strategies.
• the informing base station may then decide if there is a conflict or not, as shown in a step 34. If not, the informing cell may allocate the resources, e.g., the orthogonal resources of the informing cell according to both said resource allocation strategy of the informing cell and the resource allocation strategies received from the surrounding cells so as to reduce interference in the system.
• the resources e.g., the orthogonal resources of the informing cell according to both said resource allocation strategy of the informing cell and the resource allocation strategies received from the surrounding cells so as to reduce interference in the system.
• a step 38 is carried out to determine how to resolve the conflict. For instance, one or more rules may be defined for a case where said informing cell and a cell from said surrounding cells indicate a same strategy. Such a rule might for instance be that a cell with a smaller identification number tries to find another strategy.
• a further communication step 40 may then be necessary to inform the conflicting cell and/or receive information from that cell about a new strategy.
• the informing cell should not usually have to wait for any confirmation from other cells, it is basically free to do the desired allocation immediately. In a steady state system, the informing cell will have allocation strategies from surrounding cells available (from the past) . If the informing cell wants to change its allocation strategy, it should be able to do that immediately, but should send signaling to the surrounding cells at the same time. It could also wait until the information has reached the other base stations, but that should be implementation specific.
• the various strategies used may contain different kinds of information.
• the information might be about how much interference a cell will produce to the surrounding cells on different groups of orthogonal resources.
• orthogonal resources might for example be subcarriers or groups of subcarriers in an orthogonal frequency division multiplexed system.
• the step 30 might involve the cell informing its strategy comprising allocating a frequency range where it will produce small interference, that is, where it allocated the frequency range to user equipment near a cell center.
• the cell might inform its strategy comprising allocating a frequency range where it will produce large interference, that is, where it allocated a frequency range to user equipment near a cell edge.
• the informing and receiving may take place over interfaces between base stations of the informing cell and the surrounding cells.
• Such an interface may comprise the X2 interfaces of a long term evolution architecture shown in Fig. 1.
• the signal processor of base station 102 may take the form shown in Fig. 5 and as such comprises program code for carrying out the steps of Fig. 3.
• the illustrated transceiver 108 of the base station of course includes both a receiver and a transmitter.
• Fig. 5 shows a general purpose signal processor suitable for carrying out the signal processing functions shown above. It includes a read-only-memory (ROM) 502, a random access memory (RAM) 504, a central processing unit (CPU) 506, a clock 508, an input/output (I/O) port 510, and miscellaneous functions 512, all interconnected by a data, address and control (DAC) bus 514.
• the ROM is a computer readable medium that is able to store program code written to carry out the various functions described above in conjunction with the RAM, CPU, I/O, etc.
• the same signal processing function may be carried out with a combination of hardware and software and may even be carried out entirely in hardware with a dedicated integrated circuit, i.e., without software.
• FIG. 4 another base station 120, from a neighboring cell is shown connected to base station 102 by an LTE X2 interface.
• This interface may be uses to communicate the strategies of the neighbor base stations as shown in steps 30, 32 and 40 of Fig. 3.
• the neighboring cell 120 may also comprise a signal processor 122 and a transceiver 124 similar to that shown in the base station 102.
• the UE 100 is, by virtue of the invention, a UE with resources allocated according to the invention as indicated by the UE shown in Fig. 1. As such the architecture of Fig. 1 is improved by the UE 100 and eNode B Structures 102, 120 shown in Fig. 4.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)

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• 2008
  • 2008-08-22 RU RU2010110547/07A patent/RU2485718C2/ru active
  • 2008-08-22 WO PCT/EP2008/061026 patent/WO2009024614A2/en active Application Filing
  • 2008-08-22 EP EP08787425.1A patent/EP2193677B1/en active Active
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• 2010
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